A number of different designs and types of hose or pipe clamps are currently available. Generally, the known hose or pipe clamps include a metal strap which is fixed at one end to a separate metal housing, the housing defining a recess which has its longitudinal axis aligned with the axis of the strap. A worm screw is captured within the housing recess and cooperates with an end of the strap which is looped about an article to be gripped. For this purpose, the strap is provided with spaced recesses or slots for cooperation with the threads on the worm screw such that when the worm screw is rotated in opposite directions the metal strap loop is tightened to grip the article or loosened to free the article. The housing is attached to the one end of the strap by a number of different arrangements. In one arrangement, the housing has extended side flanges which are turned over on the underside of the strap and which have opposite tongues which extend into slots in the strap. Alternatively, the housing may be welded to the strap. Examples of the above type of clamp strap are shown in DE 3121202 and U.S. Pat. No. 5,473,798. Whilst these clamps generally function efficiently, they are not suited to being manufactured from plastics. Further, as a number of steps are required in their construction such as joining of the housing to the strap, the cost of manufacture of clamps of this type can be high. A disadvantage of the above clamps is that the housing in use is held against the periphery of the article being gripped however because the housing is often of planar form on its side adjacent the article, it will not lie flush with a curved surface around which the strap is looped. This can make tightening of the strap difficult and further when tightening occurs, the full circumference of the curved surface is not closely gripped because of the planar surface of the housing is in contact with the curved surface of the article.
U.S. Pat. No. 4,047,268 discloses a moulded plastics worm gear clamping apparatus in which the housing for the worm screw is formed integrally with a strap and extends a distance along the strap, the housing having a curved surface to match the surface of an article to be clamped. The strap is looped about the article and passed into the worm screw housing to be engaged by the screw which when tightened reduces the size of the looped strap to effect a clamping action about the article. As however, the housing forms part of the strap and is coextensive with the strap, tightening of the strap about the article will apply a radially inwardly directed force tending to cause a radial distortion of the housing leading to possible screw slippage. This will limit the extent to which the strap can be tightened and therefore limit the applications to which the strap can be put. This disadvantage is further amplified if the curved surface of the housing does not match a curved surface of the article being clamped. If the clamp is used with articles of smaller diameter, incomplete clamping of the article about its periphery is achieved leading to potential leakage in pressure applications. In articles of a larger diameter, again an area adjacent the driving head will not be evenly clamped. Thus a range of different clamps are required to suit the radius of each size article to be clamped. Further the angled outer surface of the housing creates additional problems in that radial distortion of the driving head will substantially increase the risk of the screw slipping or substantially reduce the pressure which can be applied by the clamp. Similar disadvantages to those referred to above are associated with the clamps shown in GB 2326438, DE 3400681 and U.S. Pat. No. 3,914,832.
International Publication No. WO 98/23889 discloses a metal strap clamp in which the strap is attached to or extends from the front end of the screw housing via a bearing or flange which is of greater thickness than the strap, the bearing or flange being curved to match the curve of an article to be clamped. The flange is formed integrally with the housing and rigid with the housing and the strap will bend about its join to the rigid flange when tightened thus limiting the extent to which the clamp can be applied to smaller articles. Thus again many different size clamps with flanges of different radii will be required to suit different size articles.